1. Field of the Invention
The technical scope of the invention is that of devices enabling a projectile fuse to be programmed.
2. Description of the Related Art
A fuse is an electronic or electromechanical device that enables the ignition of the projectile's explosive load to be activated.
Fuses may be of the time or proximate type or else may control the functioning upon impact on a target. They are sometimes multi-mode and in this case enable the projectile to be doted with functioning upon impact or time functioning, according to the user's choice.
Multi-mode or time fuses must be programmed before firing. Such programming is, for example, the selection of the functioning mode (multi-mode fuse) and/or the time between firing and detonation (timing information).
Today, such fuse programming is made more often than not by induction using programming coils.
U.S. Pat. No. 5,117,733 discloses an induction coil to program medium caliber projectile fuse during the rotation of the projectile in the feed star of a weapon.
This device comprises two coils: one coil to detect an approaching projectile and one coil to program the fuse. When a projectile is detected by the first coil, the second coil is activated and emits the programming signal for the fuse.
Such a device thus implements a single programming coil which has a profile selected such that part of the coil is always facing the fuse during part of the forward movement of the projectile in the weapon's feed corridor.
Such a solution is, however, extremely disadvantageous from the industrial point of view, since the energy level implemented by this single coil leads to control electronics being designed that are oversized with respect to needs. Such electronics are not highly compatible with the power networks available in the turret of a weapon system.
Furthermore, the electromagnetic losses in the weapon structure and the induced radiation are very high.
Because of integration constraints it may be necessary to ensure the programming of the fuse during a phase in which the projectile is translating along its axis. Such a displacement occurs in particular when the projectile is being introduced into the weapon chamber.
The device proposed by U.S. Pat. No. 5,117,733 is not adapted to the programming of a fuse having such a translational movement. Indeed, in the structure described by U.S. Pat. No. 5,117,733, the path followed by the projectile carrying the fuse is circular and the fuse is thus always facing the programming coil during this path with optimal coil/fuse coupling since the fuse's receiver coil is substantially facing the median zone of the programming coil where the flux is at its highest.
If such a coil is positioned in the arc of a circle along part of a rectilinear corridor, coupling is acceptable but because of the translational movement of the projectile, the projectile rapidly moves away from this coil.
The implementation of U.S. Pat. No. 5,117,733 would thus require coils of substantial size to be made that cover the length of the corridor. Such coils would consume a lot of energy. It would then be necessary for several coils to be arranged in the arc of a circle (analogous to those described by U.S. Pat. No. 5,117,733) and parallel to one another for the fuse to be constantly facing one of these coils as it translates in front of the coils.
However, this solution presents other problems.
Firstly, such coils are complicated in structure. The winding of flat wires and the assembly of ferrites tightly encircled by the loops is difficult to produce.
Then, the coils arranged side by side leave zones between the coils in which the magnetic field is reduced, thereby reducing the effectiveness of the programming and the energizing of the fuse.
Lastly, the energy needed to simultaneously power all the coils is substantial, once again leading to the definition of oversized control electronics with respect to the need.